Method for producing motor fuels



May 9, 1-939. Q WAGNER 2,157,225

METHOD FOR PRODUCING MOTOR FUELS Original Filed April 21, 1933 Con denser bed? Exblz. Gas Separal'or 7 22 I 27 Separa Z'or/ INV'ENTOR BY Cary 7297 {W ATTORNEY Patented May 9, 1939,

UNITED STATES PATENT OFFICE METHOD FOR raonuomo MOTOR FUELS Gary R. Wagner, Chicago, Ill., assignor to The Pure Oil Company, Chicago, IlL, a corporation of Ohio Original application April 21, 1933, Serial No.

Divided and this application December 4, 1935, Serial No. 52,740

17 Claims.

tained from vapor phase cracking systems, where- 4 by a large proportion of such gases are, when subjected to controlled conditions of temperature and pressure, transformed into hydrocarbon compounds, liquid at normal temperatures and pressures, and which may be used as improved motor fuels.

This application is a division of my co-pending .application Serial No. 667,255, filed April 21, 1933.

It is a primary object of the present invention to subject cracked hydrocarbon-gases containing ethylene and its homologues to conditions of elevated temperature and pressure to polymerize such gases, in part, into hydrocarbons of higher molecular weights and to accomplish this result in such manner as to provide for an increased yield of the more valuable liquid products with an accompanying decrease in the unusable permanent gas production.

For a further understanding of the invention, reference is to be had to the following description and the accompanying drawing, wherein The figure is a diagrammatic view illustrating the apparatus which may be employed in carrying the present invention into effect.

It will be understood that the apparatus has been but diagrammatically illustrated in order to serve as a flow chart and that the positional order and elevations of the apparatus illustrated is not necessarily that which may be'used in commercial operations. v Referring more particularly to the drawing, the charging hydrocarbon gas which may be of an olefinic character and obtained, for example, from the gas separator (not shown) of 'a vapor phase oil cracking system, is passed under ordinary flowing pressures of the order of 15 pounds through a pipe line I for delivery to the low pressure cylinder 2 of a two-stage compressor C. After being compressed in the cylinder 2 to a pressure of the order of 250 pounds per square inch, the gas is forced through a pipe line 3 and a heat exchanger 4 to a gas separator 5. In this separator there takes place the separation of the more readily liquefiable constituents of the charging gas from the remaining compounds which do not form liquids under the pressures specified.

The substantially liquefied compounds are removed from the bottom of the separator 5 and without any substantial release of pressure thereon, are passed to a stabilizing or fractionating column 6 through the connecting pipe line 1 controlled by valve 1, the latter line leading from the bottom of the separator 5 to a point substantially intermediate of the height of the column 6. This column may be provided with the usual internally situated baflles or trays 8, 9r other standard liquid and vapor contact means, whereby low boiling compounds entrained in the oils delivered to the column 5, and present as vapors, may be brought into intimate counter-current contact with the higher boiling liquid compounds. Those compounds which accumulate in the bottom of the column 6 as stabilized liquids are withdrawn either continuously or intermittently through the valved draw-off line 9 and possess the boiling range of gasoline. These oils may be referred to as the polymerized distillate and due to the high percentage ofunsaturated hydrocarbons which they contain, may be used directly as an antiknock motor fuel, or as a blending oil for increasing the anti-detonating value of: a lower grade motor fuel oil.

The remaining vapors or gases are withdrawn from adjacent the top of the column 6 and are passed through a pipe line ill to a suitable condenser II and thence to a separating chamber I2 in which a variable pressure usually not in excess of 250 pounds is maintained but sumciently low to permit flow from the separator 5 to the sta- 'bilizer 6. Permanent gas is removed from the top of the chamber [2 through the valved gas outlet line l3 controlled by valve l3, while the condenser cooled liquid fraction is withdrawn from the bottom of said chamber through the pipe line ll and delivered to the suction side of a pump IS. A pipe line I6 controlled by valve 5' leads from the outlet side of said pump to a heating coil ll located in a furnace l8, the latter being provided with the customary burners 3'. Also leading from the pipe line I 6 is a branch I! controlled by the valve l9, which extends to the top of the column G to provide for the passage of a reflux oil downwardly through said column to control the fractionation taking place therein.

Gases relatively rich in olefins are removed from the primary separator 5 by way of the top line 20 and are passed to the high pressure cylinconnecting pipe line 22 being employed for this pu pose- Naphtha obtained from topping plants or the like may be introduced into the system by way of the line IE or line 23 controlled by valve 23' for reforming purposes. I have found that the conditions of temperature and pressure which ob-.

tain in the coil I! for gas polymerization purposes are well suited for the reforming of naphtha into a low boiling motor oil containing high percentages of unsaturates. Thus the general utility of the present system ismaterially increased by its ability to reform naphtha without requiring additional refinery equipment for efiecting this increasingly important operation. In the coil I! the gases alone or a mixture of the gases and liquids are heated to temperatures of the order of 850 F. to 1100 F. while maintained under superatmospheric pressures varying between 500 to 2000 pounds per square inch. The sytem operates quite satisfactorily, however, when the products discharged from the coil I'I possess a temperature of the order of 950 F. to 1000 F. and a pressure of about 700 pounds.

These products are then transferred to an externally disposed reaction drum 24, which is preferably unheated from external sources, although the metallic drum may be covered by a suitable heat insulating material if desired. The drum 24 may be lined with silica or ganister, if desired, to avoid catalytic'dehydrogenation in some cases. Since the polymerizing reactions which are effected in the zone 24 are highly exothermic in character, care must be exercised to prevent thereaction compounds from attaining undesirably high temperatures, such as 1100 F. to 1200 F., since such high temperatures tend to crack or decompose the compounds, thereby causing ex cessive fixed gas formation and marked reduction in the recovery of the desired liquid products and also undesirable coke formation. Suitable pressure and temperature recording instruments 24' may be employed in connection with the reaction drum, as in other parts of the system, to enable an operator to exercise accurate control over the functioning thereof. The temperature of the products within said drum is preferably maintained at substantially 950 F. to 1025 F., together with pressures of the order of 600 pounds per square inch.

Further, regulation of the temperature in the polymerization zone, which includes the reaction drum 24, may be eifected by regulating the introduction of naphtha into the polymerizing zone, as for example, through the line 33 controlled by valve 33'. Thus naphtha may be added in such quantities so that the endothermic heat of the reactions involved in cracking or reforming naphtha approximately balances the exothermic heat produced by the polymerizing of olefins. In this manner effective control of reaction-producing temperatures in the polymerizing zone is obtained. 7

Following the completion of the desired reactions in the drum 24, the heated products are then passed through a valve controlled pipe line 25 to a cooler or heat exchanger 26 and thence to a final separator 21. This separator is maintained under a variable pressure, but usually one of the order of 450 pounds. The fixed gas, lean in olefin content, may be withdrawn from the separator 21 by way of the overhead line 28 controlled by valve 28' and removed from the system for storage or other suitable use, while the liquii fraction is withdrawn from the bottom of the separator and transferred by way of the pipe line 29 controlled by valve 29 and line 30 controlled by valve 30' and containing the pump 3|, and delivered to the pipe line 3 for passage through the heat exchanger 4, the gas separator 5, and the stabilizing column 6. A branch pipe line 32 controlled by valve 32 may be employed to divert a part of the liquid passing through the line 30 to a jet cooler 34 disposed in the pipe line 25 at the outlet of the reaction drum 24, whereby accurate control is obtained of the temperature of the products delivered to the separator 21, insuring condensation of all normal liquid-like products together with minimum formation of carbon deposit, the products discharged from the drum 24 being shock chilled to non-reacting temperatures in a very short interval of time.

The present system provides for a very high recovery of liquid oils of motor fuel boiling range from cracked refinery gases or other olefin-containing gases. It will be noted that waste or fixed gas may be withdrawn optionally through the lines I3 and 28, insuring a complete elimination of those gaseous compounds which do not polymerize, and conversely, the system provides for the subjection in a sustained manner of all hydrocarbons which under the conditions of temperature and pressure specified tend to polymerize into high boiling hydrocarbons, thus effecting the formation and recovery of a maximum quantity of liquid oils or motor fuels from a given amount of charging gas.

What I claim is:

l. The process of treating oleflnic hydrocarbon gases which comprises, passing such gases through a pipe still in which the gases are heated to a temperature of the order of 850 to 1100 F., while maintained under superatmospheric pressures varying between 500 to 2000 pounds per square inch, maintaining said gases under said conditions of temperature and pressure to transform the same in part into liquid oils possessing the boiling range of gasoline and in part into a lean gas of average lower molecular weight than the gas delivered to the pipe still, reducing the pressure and separating said lean gases from the liquid oils, merging said liquid oils with an olefinic gas charged to the process under a pressure of the order of 250 pounds per' square inch, pass-- ing the resulting mixture into a separating zone without substantial reduction in pressure thereon, removing gases relatively rich in olefins from said separating zone and charging the same under materially increased pressure to said pipe still, removing the liquid fraction from said separating zone and fractionating the latter to produce a relatively stable polymer distillate and lighter overhead vaporous products, condensing said vaporous products to remove therefrom fixed gas and a condensate, and merging said condensate with the olefinic gases delivered under high pressure to said pipe still.

2. The process of treating olefinic hydrocarbon gases which comprises, passing such gases through an elongated externally heated polymerizing zone in which the gases are heated to a temperature of the order of 850 to 1100 F., while maintained under super-atmospheric pressures of approximately 500 to 2000 pounds per square inch, maintaining said gases under said conditions of elevated temperature and pressure for a sufficient period of time to transform the same into oils liquid at normal temperatures and gases of average lower molecular weight than the gases charged to said polymerizing zone, cooling the products discharged from said'zone and separating the liquid oils from the'lean permanent gases,

merging ,said liquid oils with an olefinlc gas and charging the same under materially increased pressures to said polymerizing zone, removing the liquid fraction from said separating zone and fractionating the same to remove low boiling volatile compounds from a relatively stable polymer distillate, cooling the volatile compounds to condense a portion thereof and separating fixed gas from the condensate, and merging said condensate with the olefinic gases being delivered to said polymerizing zone.

3. In the treatment of olefinic hydrocarbon of motor fuel boiling range, continuously passing such gases through an elongated heating zone in which the gases are heated to temperatures of 850 to 1100 F., while maintained under super-atmospheric pressures of the order of 500 to 2000 pounds per square ,inch, passing said gases directly from said heating zone into an enlarged reaction zone without substantial re: duction in pressure thereon, and maintaining the gases in said reactionv zone for a sufiicient period of time to complete the desired exothermic polymerizing reactions, cooling and condensing .the products discharged from said reaction zone and partially reducing the pressure thereon, whereby to separate from said products fixed gas, and a liquid oil, merging said liquid oil with an olefinic gas charged to the process under a pressure of approximately 250 pounds per square inch, passing the resulting mixture of liquid polymers and olefinic gases under substantially the pressure last specified through a separating zone, remov-.

ing from one portion of said separating zon e gases relatively rich in olefins and charging the same under materially increased pressure to said heating zone, and removing the liquid fractions from said separating zone and subjecting the same to fractionation to obtain a relatively stable liquid polymer distillate free from undesirable low boiling constituents.

4. In the treatment of olefinic hydrocarbon gases to produce liquid polymers predominantly of motor fuel boiling range, continuously passing such gases through an elongated heating zone in which the gases are heated to temperatures of 850 to 1100 F. while maintained under superatmospheric pressures of the order of 500 to 2000 pounds per square inch, passing said gasesolefinic gases under substantially the pressure last specified through a separating zone, remoiving from one portion of said separating zone gases relatively rich in olefins and charging the same under materially increased pressure to said heating zone, removing the liquid fractions from said separating zone and subjecting the same to fractionation to obtain a relatively stable liquid polymer distillate free from undesirable low boiling constituents, condensing said low boiling constituents following such fractionation to obtain a liquid condensate and fixed gas, and merging said liquid condensate with the oleflnic gases being charged under high pressure to the heating zone.

5. 'The method of treating oleflnic hydrocarbon gases to obtain hydrocarbon liquid polymers predominantly of the motor fuel range, which comprises charging such gases to a primary stage .of compression where said gases are placed under super-atmospheric pressure sufficiently high to effect the liquefaction of the more readily liquefiable constituents present, passing said mixture of compressed gases and liquids into a prigases to produce liquid polymers predominantly liquid polymers freed of undesired low boiling constituents.

polymers predominantly of motor fuel boiling range comprising subjecting an unsaturated ole- 1 passing said gas through a second high pressure stage of compression wherein said gas is placed under a pressure of the order of 850 pounds per square inch, delivering the gas under the pressure last specified to a heating zone and therein raising the temperature of the gas to approximately 850 to 1100 F., passing the heated products released from said heating zone at a lower velocity through an enlarged externally unheated reaction zone to complete the desired polymerizing reactions, cooling the products discharged from said reaction zone and separating the remaining gas from liquid polymers, returning at least a part of said liquid polymers to thegases discharged from said primary stage of compression, and fractionating the liquid products removed from the primary separating zone.

'7. The method of polymerizing unsaturated hydrocarbon gases to obtain therefrom liquid polymers predominantly of motor fuel boiling range comprising-subjecting an unsaturated olefinic gas to a primary stage of low -pressure compression, introducing into said gas a stream of liquid polymers without substantial reduction in the degree of compression of said gas, subjecting the mixture of compressed gas and liquid polymers to separation to remove hydrocarbon gas of high olefinic content from the liquid polymers, passing said gas through a second high pressure stage of compression wherein said gas is placed under a pressure of the order 01 850 pounds per square inch, delivering the gas under the pressure.

arating zone and passing the same through a.

fractionating zone, removing from the lower portion of said fractionatingzone a polymer distillate, removing from the upper portion. of said iractionating zone low boiling vaporous constituents, condensing said vaporous constituents, separating fixed gas from the condensate thus produced, and returning said condensate in part to said i'ractionating zone and in part to the gases discharged from the high pressure stage of gas compression and which are being delivered to said heating zone.

B. In a process for the polymerization of olefinic gases at temperatures of 850 to 1100 F. and under pressures of 500 to 2000 pounds per square inch, the steps 01' separating liquid products from unreacted gases in at least three stages, the second stage being at a lowerpressure than the first stage. separating fixed gases from products in the first stage, eliminating fixed gases from the system, separating gas relatively rich in olefins from at least one stage subsequent to the first stage and recycling substantially all of said gas directly to the polymerization step, and eliminating the gases low in polymerizabie constituents separated in the other stagestrom the system.

9. In a process for the polymerization of olefinic gases at temperatures of 850 to 1100' F. and under pressures of 500 to 2000 pounds per square inch, the steps of separating fixed gases from products under high super-atmospheric pressure and relatively low temperature in a first separating stage and eliminating said fixed gases from the system, separating remaining gases from liquid products in at least two subsequent stages at lower pressures than said first stage, separating gas relatively rich in olefins from at least one stage and recycling substantially all of said gas directly to the polymerization step, and eliminating the gases low in polymerizable constituents separated in the other stages from the system.

10. In a process for the polymerization of olefinic gases at temperatures of 850 to 1100 F. and under pressures of 500 to 2000 pounds per square inch, the steps of separating liquid products from fixed gases at low temperature and at high super-atmospheric pressure and eliminating said gases from the system, separating remaining gases from liquid products in at least two subsequent stages of lower pressure than that at which fixed gases are separated, separating gas relatively rich in olefins in one of the two subsequent stages and recycling substantially all of said gas directly to the polymerization step, and eliminating gases low in polymerizable constituents from the other of said subsequent stages.

11. In a process for the polymerization of gases relatively rich in olefins at temperatures of 850 to 1100 F. and under pressures of 500 to 2000 pounds per square inch, the steps of separating liquid products from unreacted gases in at least three stages, the second and third stages being at lower pressures than the first stage, separating fixed gases from products in the first stage, eliminating fixed gases from the system, separating gas relatively rich in olefins from at least one stage subsequent to the first stage and recycling substantially all of said gas directly to the polymerization step, and eliminating the gases low in polymerizable constituents separated in the other stages from the system.

12. In a process for the polymerization of gases relatively rich in olefins at temperatures of 850 to 1100 F. and under pressures of 500 to 2000 pounds per square inch, the steps of separating fixed gases from products under high super-atmospheric pressure and relatively low temperature and eliminating said fixed gases from the system, separating remaining gases from liquid products in at least two subsequent stages at lower pressures than that at which said fixed gases are separated, separating gas relatively rich in olefins from at least one stage and recycling substantially all of said gas directly to the polymerization step, and eliminating the gases low in polymerizable constituents separated in the other stages from the system.

13. In a process for the polymerization of gases rich in olefins at temperatures of 850 to 1100 F. and under pressures of 500 to 2000 pounds per square inch, the steps of separating liquid products from unreacted gases in at least three stages, the second and third stages being at lower pressures than the first stage, separating fixed gases from products in the first stage, eliminating fixed gases from the system, separating gas relatively rich in olefins from at least one stage subsequent to the first stage and recycling substantially all of said gas to the polymerization step, and eliminating any gas, low in polymerizable constituents, that may be separated in other stages, from the system.

14. In a process for the polymerization of gas relatively rich in olefins at temperatures of 850 to 1100 F. and Under pressures of 500 to 2000 pounds per square inch, the steps of separating liquid products from unreacted gases in at least three stages, the second and third stages being at lower pressures than the first stage, separating fixed gases from products in the first stage, eliminating fixed gases from the system, separating gas relatively rich in olefins from at least one stage subsequent to the first stage, and recycling substantially all of said gas to the polymerization said gases, maintaining said gases under said conditions of temperature and pressure for a period of time sufiicient to transform said gases into liquid hydrocarbons and into residual gas of lower average molecular weight and containing a lower content of olefinic hydrocarbons than said gas passed to said pipe still, cooling the reaction products, separating said residual gas from said liquid hydrocarbons under super-atmospheric pressure, mixing said separated liquid hydrocarbons with olefinic charging gas, removing gases relatively rich in olefins from the mixture under super-atmospheric pressure below that at which residual gas is separated from liquid hydrocarbons and charging said relatively rich gases under high super-atmospheric pressure to said pipe still, and iractlonating the remaining liquid hydrocar bons to produce a stabilized polymer liquid.

16. Process in accordance with claim 15 in which the gases are heated to a temperature of the order of 850 to 1100 F. under pressure varylag between 500 to 2000 pounds per square inch. 17. Process in accordance with claim 15 in CARY R. WAGNER. 

